By way of example, the geared fluid machine can be designed as a gear pump or as a gear motor. Likewise, a design as an internal geared fluid machine or as an external geared fluid machine is possible, such that the geared fluid machine can be in the form of an internal gear pump, internal gear motor, external gear pump or external gear motor. In either case, the geared fluid machine comprises the first gearwheel and the second gearwheel. The two gearwheels mesh with each other, wherein the first gearwheel has a first toothing and the second gearwheel has a second toothing, and the two toothings at least partially engage with each other. In the following, the internal geared fluid machine will be discussed purely by way of example. Of course, the details can always be applied directly to an external geared fluid machine.
In the case of the internal geared fluid machine, the first gearwheel is designed as a pinion and the first toothing is designed as an external toothing, whereas the second gearwheel is a ring gear comprising the second toothing which is designed as an internal toothing. The pinion is arranged in the ring gear in such a manner that the two toothings mesh with each other. The pinion in this case is mounted eccentrically with respect to the ring gear. This means that the first gearwheel is rotatably mounted about a first axis of rotation and the second gearwheel is rotatably mounted about a second axis of rotation, the two axes of rotation preferably being arranged parallel to and at a distance from each other. If the geared fluid machine is designed as an external geared fluid machine, the two toothings are arranged as external toothings which mesh with each other. In this case as well, the two axes of rotation are arranged parallel to and at a distance from each other.
In the case of a design of the geared fluid machine as a pump, the gearwheels are subjected to a rotational movement, whereby a conveying effect is exerted on a fluid present in the geared fluid machine. On the other hand, if the geared fluid machine is designed as a motor, fluid is supplied to the same, causing the gearwheels to rotate. A torque, which can be tapped, is therefore made available on one of the gearwheels. The following solely addresses the pump in detail. However, the details given can always be transmitted to the motor.
As essential components, the geared fluid machine comprises the first gearwheel, the second gearwheel and the machine housing. The two gearwheels are rotatably mounted in the machine housing, particularly about the first axis of rotation and the second axis of rotation. To achieve the eccentric mounting of the two gearwheels, the two axes of rotation are arranged at a distance from each other, in particular parallel to each other. In the case of the internal geared fluid machine, the pinion is arranged in the ring gear and accordingly has an outer diameter which is less than an inner diameter of the ring gear. Both the pinion and the ring gear are essentially round in cross-section relative to the respective axis of rotation. The outer diameter of the pinion and the inner diameter of the ring gear are selected in such a manner that the outer toothing of the pinion engages in the circumferential direction with respect to the second axis of rotation only with a region of the internal toothing of the ring gear.
The first gearwheel is, for example, arranged on a drive shaft of the geared fluid machine, in particular connected to it in a torque-proof manner. The first gearwheel can therefore be driven via the drive shaft and made to rotate about the first axis of rotation. On account of the second toothing, which is in engagement with the first toothing, the rotational movement of the first gearwheel is also impressed on the second gearwheel. In the case of the internal gear pump, the first gearwheel is directly driven by the drive shaft, while the second gearwheel is only indirectly driven by the drive shaft via the first gearwheel. Both the first toothing and the second toothing have a plurality of teeth, as well as tooth gaps between the teeth. In the case of the internal gear pump and/or the external gear pump, the conveying effect is achieved by the meshing of the first toothing and the second toothing.
When any given tooth of the first gearwheel is observed during a complete rotation of the first gearwheel, this tooth temporarily engages in a tooth gap of the second toothing. Before the tooth engages in the tooth gap, fluid is present in the latter. As a result of the engagement, the fluid is preferably conveyed to a pressure side and/or into a pressure chamber of the geared fluid machine, particularly from a suction side and/or out of a suction chamber. The pressure chamber is formed, for example, in the machine housing of the geared fluid machine. If the geared fluid machine is designed as a geared fluid motor, the fluid flows from the pressure chamber toward the suction side and/or the suction chamber of the geared fluid machine, thereby driving both the first gearwheel and the second gearwheel. To this extent, the geared fluid motor constitutes the kinematic reversal of the geared fluid pump.
The at least one axial washer is arranged in the machine housing, and lies at least partially against an end face of the first gearwheel and/or an end face of the second gearwheel. The axial washer functions as a seal, in particular of the pressure side against the suction side, such that the fluid present in the geared fluid machine cannot flow past the end face of the first gearwheel and/or the second gearwheel. Of course, an axial washer is preferably arranged on either side of the first gearwheel and the second gearwheel. However, in the following, only one of these axial washers will be discussed, although the details given can always be applied otherwise. By way of example, the axial washers are designed to be symmetric to each other, or are even present as common parts.
In order to always achieve a reliable seal by means of the axial washer, the latter is arranged in the machine housing with axial play with respect to the axis of rotation and/or the axes of rotation. In order to press the axial washer during operation in the axial direction toward the first gearwheel and/or the second gearwheel, in particular against the first gearwheel and/or the second gearwheel, the axial washer has a pressure field on its side facing away from the gearwheels in the axial direction. The pressure field is preferably in the form of a depression in the axial washer which is preferably closed on the edge thereof—that is, possesses a circumferential edge. The depression only partially passes through the axial washer in the direction of the gearwheels—not completely. In this respect, it has a continuous base.
At least during the operation of the geared fluid machine, the pressure field and/or the depression is subjected to the force of pressurized fluid. The fluid in this case is preferably the same as that which is present in the pressure chamber and/or the suction chamber of the geared fluid machine. For example, the pressure field is fluidically connected to the pressure side of the geared fluid machine, particularly via at least one flow channel which is at least partially or completely constructed in the machine housing. Optionally, a throttle and/or a diaphragm can be included in the flow channel in order to adjust the desired pressure in the pressure field.
The pressure field is surrounded by the circumferential seal which is arranged on the axial washer. By way of example, the seal is fixed in a depression of the axial washer and/or a depression of the machine housing. The seal completely surrounds the pressure field and is accordingly designed as a circumferential seal. Observed in the axial direction, the seal lies on one side thereof against a bearing surface of the axial washer, and on the other side thereof against a second bearing surface of the machine housing, wherein the bearing surfaces are preferably arranged parallel to each other. Because of the sealing of the pressure field by means of the seal, the axial washer is pressed by the pressurized fluid present in the pressure field in the direction of the first gearwheel and/or the second gearwheel, such that the axial washer preferably lies against the end face of the first gearwheel—or of the second gearwheel.
By way of example, an internal gear pump is known from DE 10 2012 213 771 A1, having an axial washer which lies against the end faces of a ring gear and of a pinion of the internal gear pump to laterally limit a pump space, and which has a pressure field on an outer side facing away from the ring gear and the pinion, which is sealed with a sealing ring which encloses the pressure field. In this case, the internal gear pump has a sealing arrangement with the sealing ring, which has the shape of a contour of the pressure field and an L-shaped ring cross-section, and with an elastic ring which engages internally in the L-shaped ring cross-section of the sealing ring.